Torque controlled fuel supply system



April 7, 1942.

M. J. KITTLER ET AL I TORQUE CONTROLLED FUEL SUPPLY SYSTEM "Filed March 4, 1940 2 Shget-s-Sheet l M/L TU/VJ/F/TZZEF ATTORNEY April 7, 1942. J. KlT' lLER ETAL TORQUE CONTROLLED FUEL SUPPLY SYSTEM 2 Sheets-Sheet 2 Filed March 4,- 1940 M/LMN J 11777256 .57/9/VAEY M .flfl/Z LE INVENTOR TTQRNEY Patented Apr. 7; 1942 TORQUE oos'morzzn rum. SUPPLY srs'ram mam VJ. Kittler and smile impale, Detroit, Mich... assignors to George M. Holley and Earl Holley Application March 4, 1940, Serial N6. 322,104

ZiClaims.

The object of this invention is to control the fuel supply of a fuel injection internal combustion engine in. which an independent supply of fuel is intermittently admitted to each cylinder,

from an engine driven pump and in which the air supply is throttled and in which a supercharger is interposed between the throttling means and the engine.

With such an arrangement the air admitted to the cylinder can be both above-and below atmospheric pressure so that the air density will vary widely both-with the position of the throttle and with the altitude and to a lesser extent with the temperature of the air. It is customary with such engines to maintain-the mixture ratio in the neighborhood of 7 parts by weight of fuel to 100 parts by weight of air, and this mixture ratio is maintained throughout the cruising lean" range which is the range below 70% of the mean effective pressure in the cylinder, which is the exact equivalent of the engine torque. When this amount of torque is exceeded, that is to say, when the throttle is opened wide below 15,000 feet altitude. a richer mixture is needed and in the case of air cooled engines, a mixture ratio ashigh as 11 parts by weight of fuel to 100 parts by weight of air is needed to prevent the cylinders overheating. v

The specific object of this invention is to control the discharge of the fuel pump so that when cruising lean and developing less than 70% of the maximum mean effective pressure, the mixture is controlled by the density of the air and when developing power so that the mean effective .pressure and the torque exceed 70% of the maximum, by the joint effect of both air density and engine torque. In the drawings:

Fig. 1 shows diagrammatically the preferred form of our invention including a servo mechanism to insure the effective control of the pump by a device responsive to the density of the air.

Fig. 2 shows diagrammatically the simplified form of our invention omitting the servo mechanism.

Fig, 3 shows diagrammatically the torque responsive device.

In Figures 1 and 2, II is the fuel pump driven by the shaft II which normally rotates at half engine speed one four cycle engine and at engine speed on a two cycle engine. This pump is shown with four outlets but will have as many outlets as there are cylinders. .This pump deat which the mixture ratio is made richer.

livers fuel at a high pressure to the fuel injection;

charged is determined by the position of a rack I 2 and it is the movement of this rack by the control mechanism that constitutes the basis for this invention.

In Figure 1 this rack I2 is moved by the piston l3 which is controlled by the valve H which controls the admission of high pressure oil from the pipe ll into the cylinder and permits the oil to escape from the. cylinder through the passage It. The movement of the valve H is determined by the spring 43 within the partially evacuated bellows H, which bellows has an adjustable support IS. The other end of the valve ll engages with and compresses a spring IS. The other end of this spring I! engages with a movable seat 20 pivotally mo n ed on a lever 2| which has a movable fulcrum 22. This lever 21 'moves a link 3! pivotally connected with a lever 32 mounted on a stationary fulcrum 33, which lever 32 carries the fulcrum 21 andthus moves the lever 2 I. A spring 34 engages with a movable stop 35 which determines the initial movement of the diaphragm 29 away from its stop 30. The

- diaphragm 29 moves to the left whenever the pressure in the chamber 25, which pressure reflects the torque of the engine, exerts a force on the rod ll greater than that exerted by the spring 3], plus that force exerted by the spring l9 acting through the lever 2|. Hence the adjustment of the stop 35 determines the torque at which the rod 3| departs fromthe stop 30 and carries with it the fulcrum 22 which thereupon moves to the left. This torque is arranged to be substantially greater than 50% of the maximum. torque devel oped by the engine. Therefore, the stop 3! is the means for determining the percentage of torque The lever 32 is formed with a cam surface 6! so that the spring 34 is shortened as it is compressed, thus giving a mixture ratio for the higher torques which at first rapidly becomes richer and becomes richer less rapidly thereafter.

A lever 36 controls a throttle 3T controlling the system of the engine. The amount of fuel dis- 55 air entrance iii'wliich leads to the supercharger shown diagrammatically at 39 which delivers compressed air to the engine through a number of outlets including the passage 40. The compressed air from the supercharger l9 communicates through the passage 4| with the chamber 42 in which is mounted the compressible evacuated bellows II, inside which is the compressed spring 43, which is balanced against the compression spring ll.

The inside of the bellows 48 is partially evacuated so that to a limited'extent 43 responds to temperature as well as to pressure. In order that this will function, a return by-pass ensures the circulation of air around the bellows 43 so that the temperature within the chamber 42 corre-- sponds to the temperature in the air passages leading to the engine cylinders.

The torque responsive device 27 in Figures 1 and 2 is no part of this invention. However, it is not as well known as the fuel pump l; therefore, it is shown in Figure 3 in detail. In Figure 3, 83 is the driving shaft which carries a gear 84, which engages with the gears 65, 58, 61 mounted on the spider through which the torque is transmitted. The gears SI, 68, 61 engage with an internal gear SI. which has only a limited movement and is connected with a piston 68 in the cylinder H in which is generated the hydraulic pressure transmitted through the pipe 28 which leads to the diaphragm chamber 25.

If the throttle 31 is opened rapidly there will be a time lag in the functioning of the various mixture control devices shown here. During this interval of time th mixture may become too weak and a dangerous condition might result. To overcome this, I have shown in broken lines in Figure l a lever "connected through a link II with a piston I3 located in a cylinder 14 which is connected through a check valve 15 with a fuel entrance ipe 16. A fuel outlet 11 discharges into the center of the supercharger 39. A check valve 18 in the outlet performs a similar function to that of the. check valve 15 in the fuel entrance. when the throttle is opened rapidly the piston 13 descends in the cylinder I4 and fuel is ejected through the fuel outlet 11.

Operation- In Figure 1, when the throttle lever 38 is rotated clockwise and the throttle opened, the pressur in the chamber 42 increases, thus collapsing the bellows l1 and compressing the spring 43, thus permitting the spring I! to move the valve l4 to the right, which movement admits oil pressure to the right of the piston l3, which moves the rack 12 to the left, carrying the lever II to the loft, reducing the compression of the spring l9, permitting the valve I4 to return to its original position, thereby re-establishing equilibrium between the spring l9 and the spring 43. Hence, as the pressure in the chamber 42 increases, the rack l2 moves to the left, and by suitably proportioning the contours of the pump liner, the desired constant mixture is obtained.

This constant mixture ratio is quite satisfactory until 70% of the rated brake mean effective pressure is reached. When this is reached, or at 135 lbs. per sq. in., it is desirable to add extra fuel so that instead of the cruising lean mixture ratio, a progressively richer mixture is added to develop the maximum brake mean effective pressure and also to prevent the engine overheating, as practically all military and most commercial planes are air cooled for obvious to add extra fuel at maximum power to prevent the cylinders overheating. The ability to take off promptly when hot has value in warfare. This extra fuel is added by moving the fulcrum 22 to the left, which carries with it the rack 12, and thus increasing the richness of the mixture and thus gives the desired mixture ratio at maximum power.

In Figure 2, the servo mechanisms shown in Figure 1 ar omitted. In this figure the diaphragm 23 engages with the compression spring 44, which compression spring is regulated by means of the lever which is operated by the link 46 and the hand-operated lever 41. The diaphragm 28 is connected through the link 4! with the lever 49 which is connected through the link 50 with the cam 5i pivotally mounted at 52 on the extension 63 carried by the fuel pump iii. The cam 5| engages with the roller 53 which is held in contact with the cam 5! by the compression spring 54. The chamber 42 is connected with the outlet 40 fromthe supercharger 39 and the bellows H is supported by the tension spring 55 which is supported by the adjustable screw 56 and engages with the rod 51 extending from the bellows H. The rod 51 is pivotally connected with the lever 49.

If ten inches of mercury air pressure, that is to say, two-thirds below the normal atmospheric pressure of thirty inches, is maintained inside the bellows ll, the limited amount of air or other gas that it contains will give a partial correction for changes in temperature. Practically speaking the mixtur ratio will thus be corrected for both pressure and temperature, that is, for air density. Hence th desired correction forair density will be practically obtained by the use of a partially evacuated bellows. Hence the fuel ratio will be maintained approximately constant :egardless of changes in altitude or air temperaure.

In Figure 2, when the supercharger pressure increases the bellows i1 moves to the left under the'influence of the increased pressure in 42, stretching the spring 55. The lever 49 moves over to the left counterclockwise. The cam Ii moves to the left, the rack l2 moves to the left, and gives an increased richness to the mixture. When the torque admitted to the chamber 28 behind the diaphragm 29 exceeds. the predetermined pressure determined by the lever 41 which compresses the spring 44, the link 48 moves to the left and carries the lever 49 clockwise, which carries the cam 51 counter-clockwise, which pushes the rack I! over to the left and again increases the mixture ratio. Hence the only difference between Figures 1 and 2 is the absence of the servo mechanisms which have been omitted for the sake of clearness and simplicity. It is recognized that it is difllcult to get the bellows il sufllciently powerful to operate without the assistance of a servo mechanism, such as is shown in Figure 1. On the other hand, the presence of a servo motor confuses the description and detracts attention from the novel combination of torque responsive means with a means responsive to air density to correct for both air density and engine torque. The manual control lever 41 (Figure 2) is an over-riding adjustment lor selecting the critical value of the engine torque at which the engine torque becomes effecti.e in causing additional fuel to be supplied in excess of that called for by the air density control means. The pilot thus has means for semit' the additional fuel and of course, he will admit the extra fuel at a lower torque on a hot day than on a cold day, as the tendency for an engine to overheat is greater on a hot day than on a cold day.

What I claim is: 1. A fuel control unit for an internal combustion engine having a fuel injection pump adapted to supply fuel to said engine and an engine torque responsive device adapted to create hydraulic pressure in proportion to the torque of the engine, a moving wall responsive to said hydraulic pressure, a lever operatively connected at one end to said wall, an air supply passage for said engine, throttling means therefor, means responsive to the density of the air entering said engine for regulating the discharge of said fuel pump, said means being connected to the 2,279,048 lecting the torque above which he. desires to ad-' pressure in proportion to the torque of th engine, a moving wall responsive to said pressure, an air supply passage for 'said engine, throttling means therefor, means responsive to the density of the air, and means responsive to the combined action of said air density responsive means and said engine torque responsive means for controlling the delivery of said fuel pump.

3. A fuel control unit for an intemai combustion engine having a fuel injection pump adapted to supply fuel to said engine comprising an engine torque responsive device adapted to create hydraulic pressure in proportion to the engine torque; a moving wall responsive to said hydraulic pressure, a lever operatively connected to said wall, an' air supply passage to said engine, throttling means therefor, means responsive to th density ofthe air entering said engine, said means being connected to said lever, pump regulating means also connected to said lever at a point which is responsive both to the hydraulic pressure and to the density of the air, the first mentioned regulating means being operated only after the torque exceeds substantially 50% of the maximum torque developed by the engine, the means responsive to air density being operative throughout the entire working range of the engine.

MILTON J. mmnn. STANLEY M. UDALE. 

